Why am I getting core dumped? [closed] - c

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Closed 10 years ago.
Please help me. I can't figure out why I get a core dumped when I run this program. Before returning anything I can print all_albums_p just fine. Why am I getting core dumped?
#include "music_server.h"
struct album_ {
int num_tracks;
char **tracks;
int **playlist_hits;
};
typedef struct album_ album;
album *parse_album(FILE *album_file,int *number_of_albums){
int number_of_album,number_of_tracks,number_of_charaters;
int i,j;
char dummy_space;
int *p;
fscanf(album_file,"%d", &number_of_album);
*number_of_albums = number_of_album;
album *all_albums_p = (album *)malloc(sizeof(album)*number_of_album);
for(j=0;j<number_of_album;j++){
fscanf(album_file,"%d", &all_albums_p[j].num_tracks);
all_albums_p[j].tracks = calloc(all_albums_p[j].num_tracks,sizeof(char));
all_albums_p[j].playlist_hits = calloc(all_albums_p[j].num_tracks,sizeof(int));
/*Line 27*/ for(i=0;i<all_albums_p[j].num_tracks;i++){
fscanf(album_file,"%d", &number_of_charaters);
all_albums_p[j].tracks[i] = (char *)calloc(number_of_charaters+1,sizeof(char));
all_albums_p[j].playlist_hits[i] = (int *)malloc(sizeof(int));
all_albums_p[j].playlist_hits[i] = 0;
fscanf(album_file," ",dummy_space);
fscanf(album_file, "%[^\n]s", all_albums_p[j].tracks[i]);
}
}
return all_albums_p;
}
main(int argc, char *argv[]){
int i,j;
int *number_of_albums,*number_of_tracks,a;
a=0;
number_of_albums = &a;
album *all_tracks_ptr;
album_file = fopen(argv[1],"r");
transaction_file = fopen(argv[2],"r");
if((album_file == NULL) || (transaction_file == NULL)){
printf("Either %s or %s could not be open");
}else{
all_tracks_ptr = parse_album(album_file,number_of_albums);
int number_of_tracks[*number_of_albums];
}
}
errors:
Bus Error (core dumped)
(gdb) bt
#0 0xff277c9c in _smalloc () from /lib/libc.so.1
#1 0xff277d10 in malloc () from /lib/libc.so.1
#2 0xff263830 in calloc () from /lib/libc.so.1
#3 0x00010dd8 in parse_album (album_file=0xff3675bc,
number_of_albums=0xffbff894) at functions.c:27
#4 0x00010b80 in main (argc=3, argv=0xffbff90c) at project3.c:19

Answer 1

You should allocate sizeof(char*) below instead of sizeof(char)
all_albums_p[j].tracks = alloc(all_albums_p[j].num_tracks,sizeof(char*));

Answer 2

Since that looks like a Unix message ("Bus Error (core dumped)) I will assume you are using some flavor of Unix.
So, compile your program with debugging info output turned on and with optimization turned off. If you're using gcc or something gcc-compatible, that would be the -g -O0 command line options.
Then run your program and have it crash. Locate the core dump (I'll call it corefile in this example) and then type:
gdb programname corefile
Then when you get the gdb prompt, type bt (for backtrace) to see the program's stackframe. That will tell you where the program crashed and you can examine that part of your program more closely.
Update:
I think your problem is here:
all_albums_p[j].tracks = calloc(all_albums_p[j].num_tracks,sizeof(char));
album.tracks is defined as char**. However, what you're assigning to all_albums_p[j].tracks is a block of memory the size of num_tracks char. You need to assign to it a block of memory big enough to hold num_tracks char *. So you probably need to change the line to:
all_albums_p[j].tracks = (char **) calloc(all_albums_p[j].num_tracks,sizeof(char *));

Answer 3

Use a debugger or valgrind and figure out what line the problem is occurring on. Then you will know what part of your code is bad.